Induction coupling for braking roller drive on the flat-folding device

ABSTRACT

The invention relates to a lay-flat equipment ( 1 ) for films or tubular films ( 6 ) extruded by blown film extrusion installations ( 1 ). Said installation ( 1 ) comprises at least one roller ( 16 ), which ( 16 ) guides the walls of the film or the tubular film ( 16 ) [sic:  6 ], wherein the lay-flat equipment ( 1 ) comprises at least one device (B,  24, 22, 23, 21, 20, 25, 26 ) for influencing the rotational speed of the roller ( 16 ), said device (B,  24, 22, 23, 21, 20, 25, 26 ) comprising means ( 9 ) for providing a torque (B,  24 ) that can be transferred onto the roller ( 16 ) by means of transfer devices ( 22, 23, 21, 20 ).  
     Unlike prior art devices, the inventive device is provided with transfer devices ( 22, 23, 21, 20 ), which allow a slip between the roller ( 16 ) and the devices ( 24 ) for providing a torque.

This is a nationalization of PCT/EP04/010626 filed 22 Sep. 2004 andpublished in German.

The invention relates to a lay-flat equipment for films or tubular filmsaccording to the preamble of claim 1. Lay-flat equipments of this typeare known. They are used especially in extrusion devices, which extrudetubular films with the help of a blown film die. These tubular films areeither laid flat completely or are sub-divided previously into films ortubular films and are laid flat subsequently. The lay-flat equipmentusually consists of lay-flat plates and/or lay-flat frames placedagainst one another in a wedge-shaped manner, said plates and/or framesbeing loaded with surfaces, on which the film to be laid flat and/or thewalls of the tubular film slide along. It has been suggested in recenttimes that rollers be used instead of these surfaces. This isillustrated, for example, in DE 101 40 577 A1 and EP 795 391 A2. Thepurpose of the use of the rollers is to prevent damages of the freshlyextruded films caused by the lay-flat equipments. However, devisingmeasures for further reducing these damages continues to be among thepreoccupations of those of skill in the art. Therefore the presentinvention is based on the aforementioned devices and its object is tofurther prevent the mentioned damages of the film. This object isachieved by the features of the characterizing part of claim 1. In thewords of the present application, torque can be provided both by amotor, thus an actively torque-generating unit as well as by a brakemechanism.

This concept is based on the fact that a brake mechanism provides“negative torque” while a motor provides “positive torque.” Positivetorque supports the proper movement of the film, negative works againstit. Either brakes or motors can be advantageous in case of differentfilms. A design form of the torque transfer devices according to theinvention is of great advantage in case of both types of torque transferdevices in the sense of the present invention. Both a brake as well as amotor can bring about damages on the film due to the rigid manner oftorque provision that is peculiar to it. Therefore the present inventionteaches to provide torque transfer devices, which allow a slip betweenthe roller and the means for providing the torque. Here, a slip ispresent at least, when the roller rotates at a different speed per unitof time than the driving journals of the means for providing the torque.The torque transfer devices are often advantageously embodied as acoupling. Force-fit connections in the sense of the usual definitionsand the present invention are connections, in which the parts which tobe connected are held by a force, e.g., a frictional force, in theiropposite position. In the case of an exceedance of a certain forceand/or in this case a certain torque, a movement of the two connectedparts towards each other becomes possible (often the parts to beconnected slide toward one another), without irreproducibly destroyingthe connection in doing so. An example of a force-fit power transmissionis friction gears and also friction couplings. Friction usually plays arole even in hydraulic couplings, as a result of which they are usuallycategorized under the term “frictional force-fit connections.” Bringingabout or supporting a force-fit connection using a magnet is among themeasures, which can be consulted for an advantageous embodiment of thepresent invention. Here it is immaterial whether the total force forimplementing the force-fit connection is provided by the magnet, orwhether the magnet presses together, for example, two disks, which ontheir part, bring about the force-fit connection by their friction. Inall types of a force-fit connection, it appears to be advantageous ifthe force flow surfaces turned towards one another and using which theforce-fit connection takes place and using which the torque is finallytransferred, are reducible or increasable. Due to this, the amount ofthe maximum torque transmission can be defined and/or varied. Usuallyforce flow surfaces are the surfaces of plate-shaped coupling pieces,said surfaces being turned towards one another, wherein said couplingpieces pressed together using any force thus create the force fit orfriction fit. If several such transfer devices are provided, it appearsadvantageous to interconnect this multitude of force flow devices sothat a relative movement of the force flow surfaces assigned to thetorque providing means opposite to the force flow surfaces assigned tothe rollers leads to a change in the maximum transferable torque in alltransfer devices. Another alternative to change the maximum transferabletorque of such a force-fit connection provides a torque transfer device,which implements the force-fit connection with the help of anelectromagnet. In case of such an electromagnet, the field intensity canbe changed by a variation of the current intensity, with which theelectromagnet is controlled. Due to this naturally even the strength ofthe force-fit connection is changeable. The changeability can play animportant role for the film quality especially during order changes orwhen determining damages, for example using sensors observing the filmand is thus markedly advantageous when embodying the present invention.

Additional embodiments of the present invention are based on thisdescription and the claims.

The individual figures illustrate:

FIG. 1 a sketch of a blown film extrusion installation.

FIG. 2 a sketch of a lay-flat equipment with a brake mechanism for eachroller.

FIG. 3 a sketch of a lay-flat equipment with a brake mechanism forseveral rollers.

FIG. 4 a sketch of a roller and a torque transfer device, which areloaded with two drive disks arranged radially relative to each other.

FIG. 5 another sketch comprising a torque transfer device and a roller,which is equipped with a coupling.

FIG. 6 a sketch of a roller and a torque provision means, which areconnected using force flow disks.

FIG. 7 the arrangement shown in FIG. 6, wherein the force flow disks aremoved against each other.

FIG. 8 the arrangement shown in FIG. 7, wherein several pairs of motorsand drive disks are shown.

FIG. 9 an arrangement according to the invention of a roller and atorque transfer device comprising an electromagnet and a powercontroller.

FIG. 10 two force flow disks shown against one another.

FIG. 11 two force flow disks having magnets.

FIG. 1 illustrates a lay-flat equipment 1, which consists of twolay-flat devices 7 placed against one another in a wedge-shaped mannerand having rollers 13. The lay-flat equipment 1 is a part of a blownfilm extrusion installation 2 for the production of tubular films 6.

The flow of material in the blown film extrusion installation starts atthe supply funnel 4 of the extrusion 3 using which plastic rawmaterial—preferably in granulate form—is supplied to the extruder 3. Asis generally known, the extruder 3 transforms the raw material (notillustrated) into a semi fluid form, which is supplied to the blown filmdie 5 by way of the connecting piece 14.

The blown film die 5 extrudes the tubular film 6, which is laid-flat inthe lay-flat equipment 1, which consists of two lay-flat devices 7,placed against one another in a wedge-shaped manner. The squeegeerollers 8 additionally squeeze the laid-flat film 9. The laid-flat filmmoves over rollers 10 to the winding device 11 and is wound up there onthe roll 12.

Blown film extrusion installations of this have been known for a longtime and therefore exist in all possible embodiments. Thus it iscustomary to first supply the laid-flat film 9 after the squeezingprocess to a so-called oscillating unit in order to improve the windingquality. Such an oscillating unit is not shown in the embodimentillustrated.

FIG. 2 illustrates the lay-flat equipment 1 having two lay-flat devices7, also called lay-flat plates 7 that are arranged in a wedge-shapedmanner relative to one another. The tubular film 6 moves in the feeddirection of the film, which is indicated by the arrow 19, though thelay-flat equipment 1 and in doing so slides along the rollers 13. Abrake mechanism 15 is assigned to each of the braking rollers 16. FIG. 2also illustrates two sensors 18, which are held above and below thelaid-flat film 9. These sensors examine the film for damages and folds.They are preferably optical sensors. Such sensors can also be arrangedbetween the rollers 16 or roller groups 17. Such arrangements facilitatethe assignment of the damages or folds to the rollers causing them.

FIG. 3 illustrates a lay-flat equipment 1 having unbraked rollers 13 andbraked rollers 16, wherein in this embodiment the braked rollers of alay-flat device 7 are each braked by a brake mechanism 15. Here thebraking force and/or the torque is transferred using belts (notillustrated). The rollers braked by a brake mechanism belong to a groupof rollers 17.

In all three figures, the control and regulating devices, control lines,electricity cables and the like were not shown for illustrationalreasons.

FIG. 4 illustrates a sketch of an arrangement of a roller 16 accordingto the invention and a torque providing means 24 of a lay-flat equipment1. The roller 16 is provided with a driving journal 22 and the torqueproviding means 24 are equipped with a driving journal 23. Drive disks21 and 20 are attached on the driving journals 22 and 23. The peripheralsurfaces of both these drive disks 21 and 20 contact one another and inthis way define a force-fit connection 27. The peripheral surfaces ofboth the drive disks are smooth and advantageously processed from anelastic material such as rubber. This arrangement of roller and torqueproviding means 24 is especially suitable for implementing thearrangements of rollers 16 and torque providing means 24, as illustratedin the FIGS. 2 and 3. An illustration of the additional elements of thelay-flat equipment, as for example, illustrated in the first threefigures and as required, for example, in order to hold and/or supportthe rollers 16 and the torque providing means 24, is omitted here as incase of the FIGS. 5 to 9.

FIG. 5 illustrates a sketch of another function pair made of a roller 16and a torque providing means 24. Here also, the driving journals 21[sic: 22] and 22 [sic: 23] can be seen. These driving journals areconnected to a coupling 25, which is simply illustrated as a rectanglealmost in the form of a blackbox. This coupling can be a customaryfrictional coupling or it can represent a gear coupling, or even ahydraulic coupling. As specified in the claims, the characteristic ofthe coupling 25 or of a coupling generally in the sense of the presentapplication is the separability of the torque providing means 24 and theroller 16. It follows from this description that even an equipmentaccording to FIG. 4 or according to the subsequent figures can beimplemented as a coupling, if the corresponding drive disks 21 and 20 orforce flow disks 25 and 26 in the subsequent figures can be separated.What naturally stands out when comparing FIGS. 4 and 5 is that in FIG. 4the roller 16 and the torque providing means 24 follow one another inthe radial direction r of the roller 16. In FIG. 5 these two elements 16and 24 are arranged in such a way that they follow one another in theaxial direction of the roller 16. The higher installation length in theaforementioned axial direction z of the roller 16 is naturally among thedisadvantages of this arrangement. The advantages, as shown in FIGS. 6to 9, are that it is usually simpler to provide drive disks or forceflow disks, which comprise a large force flow surface having a largeopposite overlapping surface.

In FIG. 4, the contact surface between both the drive disks 21 and 20 israther small. As mentioned before, the FIG. 6 also illustrates anarrangement of a roller 16 and a torque providing means 24. The drivingjournals 22 and 23 of these two elements follow one another in the axialdirection z of the roller 16, as illustrated in FIG. 5. They areinterconnected by both the force flow disks 25 and 26, which compriseforce flow surfaces that are turned towards one another and contact oneanother and in this way define the force-fit connection 27. The forceexisting between these two force flow disks can be applied in that thetwo disks are pressed on top of one another by an external force and afriction arises in this way, which prevents a slipping of the disksagainst one another during the circular motion till a maximum torquetransmission is exceeded. However, it is also possible to provide theforces using suitable measures inside the two force flow disks 26 and25. Thus it is possible, to equip one or both the disks 25 and 26 withmagnets, so that a magnetic attraction results between opposite magneticpoles or between the magnet and the ferromagnetics or in any othermanner.

In each of the mentioned cases and in each of the cases in which aforce-fit connection takes place between force flow surfaces of theforce flow disks 25 and 26, it is possible to change the amount of themaximum torque transmission between both the disks 25 and 26 by carryingout a displacement of the two force flow disks 25 and 26 in the radialdirection of the roller 16 and/or of the disks 25 and 26, so that asillustrated in FIG. 7, the contact surface and/or the surface of theopposite overlap of both the force flow disks 25 and 26 is changedand/or reduced, as illustrated. In this connection it must be pointedout that it is not absolutely necessary for the two force flow disks tobe in direct contact. Thus, especially in case of the use of magnets,even an additional disk can be affixed or even a gap can exist betweenboth the force flow disks. Inspite of that, the magnetic attractiveforces will ensure a certain torque transmission between the two disks.Similar alternatives exist in case of the use of hydraulic couplingsand/or force-fit connections, which are created with the help of liquidsor similar media between two disks. Such measures are also reproduciblefor a person of skill in the art against the background of the presentinvention.

A similar measure for changing the transferred torque, as in FIG. 7, istaken in FIG. 8. However, FIG. 8 illustrates several function pairs madeof roller 16 and torque providing means 33 a and 33 b. It is illustratedusing the connecting rod 29 that the two torque providing means 24 a and24 b are interconnected, so that they can be displaced in common in theradial direction of the rollers 16 a, b and c. In this commondisplacement both the contact surfaces are reduced. Another differencefrom FIG. 7 is that the force flow disk 25 b of the function pair 33 balso receives force transferred for the operation of the roller 16 c. Itpasses over this torque using the chain 30 to the drive disk 21 c of theroller 16 c. Using the measures, as illustrated in FIGS. 7 and 8, it isalso possible to change and/or to reduce by different amounts or even ata different proportion the contact surfaces of different drive diskpairs 25 a, 26 a, 25 b, 26 b by a suitable geometric design of therelations of the different drive disks 25 and 26 with respect to oneanother, by a suitable arrangement of the same in a lay-flat equipmentand by the determination of a suitable axis of motion for the commonmovement, in case of a common movement from first drive disks to seconddrive disks. In this manner, it is possible to variably change themaximum torque to be transferred, which is decisive for the start of aslipping movement. The advantages of such a measure are similar to thoseof providing a different torque for different rollers.

FIG. 9 illustrates again an arrangement, which is very similar to thatshown in FIG. 6. However, the power controller 32, which is connectedusing the connecting cable 31 to the force flow disk 26, is alsoillustrated in FIG. 9. The illustration of the power controller 32 andthe electricity cable 31 is also naturally a sketched illustration.Normally, the electricity cable would have had to be guided using thedriving journal 23 to the force flow disk 26 in order to remainoperative. However, it should be indicated using the two additionallyillustrated characteristics 32 and 31 that an electromagnet 35 is alsosuperbly suitable for changing the maximum torque that can betransferred using the force-fit connection 27. As mentioned already,this change takes place primarily using a changing current intensitywith which the coils of the electromagnet 35 are loaded. This changeinvolves a change in the magnetic field. An embodiment of the presentinvention having an electromagnet 35 can, however, be combined randomlywith other embodiments of the invention.

The FIGS. 10 and 11 once again illustrate larger picture details havingthe force flow disks 25 and 26 and clarify the location of the flowsurfaces 36 and 37 relative to one another.

FIG. 10 illustrates an arrangement without magnets 34. The interspacebetween the force flow surfaces 36 and 37 is overstated in FIG. 10. Inreality such an arrangement is usually based on the fact that the forceflow surfaces 36 and 37 lie on one another and create the friction inthis manner. The force required for this purpose can be transferred ontothe disks 25 and 26, for example, using the two driving journals 22 and23. The torque transfer then takes place due to the friction betweenboth the disks. As previously mentioned, it is also possible, inprinciple, to leave a gap between the force flow surfaces 36 and 37 andto arrange in this gap, for example, a hydraulic liquid, which conveys africtional force to the force flow surfaces.

Another alternative to transfer force over a longer distance isillustrated in FIG. 11. Here magnets 34 are arranged in both the forceflow disks 25 and 26. These magnets form function pairs, each of whichconsists of magnets of the two disks, which are arranged in these twodisks in opposition to one another and in a way are arranged in ananti-polar manner relative to one another, which leads to an attraction.It is thus also possible to transfer force by means of a magnetic gap.However, usually when using such magnetic couplings even friction canplay a role, that is, the magnets provide the force which presses boththe force flow disks 25 and 26 together and in this manner leads to thenecessary friction between the force flow surfaces 36 and 37. It canalso be easily understood based on FIG. 11 that a displacement of one ofthe two force flow disks 25 and 26 even by small amounts in the radialdirection of the roller r leads to a considerable reduction of the forcebuilt-up between the magnets 34 of the two disks 25, 26. Thus themaximum torque transferable by the force flow disk 26 onto the forceflow disk 25 is reduced and thus it is ensured that a slipping occurseven at a lesser torque. List Of Reference Symbols  1 Lay-flat equipment 2 Blown film extrusion installation  3 Extruder  4 Supply funnel  5Blown film die  6 Tubular film  7 Lay-flat device/Lay-flat plates  8Squeegee rollers  9 Laid-flat film and/or laid-flat tubular film 10Transport rollers 11 Winding device 12 Film roll 13 Rollers 14Connecting piece 15 Brake mechanism 16 Rollers 17 Group of brakedrollers 18 Sensors 19 Arrow in the conveying direction of the film 20Drive disk of 24 21 Drive disk of the roller 16 21c Drive disk of theroller 16c 22 Driving journal 23 Driving journal of 24 24 Motor orbrake, means for providing a torque 25 Force flow disk of roller 16 26Force flow disk of roller 24 27 Force-fit connection 28 Arrow in ydirection 29 Connecting rod 30 Drive chain 31 Electricity cable 32 Powercontroller 33 a, b Function pair made of 16 + 24 34 Magnet 35Electromagnet 36 Force flow surface of 26 37 Force flow surface of 25 3839 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

1. Lay-flat equipment (1) for films or tubular films (6) extruded byblown film extrusion installations (1), said installation (1) comprisingat least one roller (16), which (16) guides the walls of the film or ofthe tubular film (16) [sic: 6] wherein the lay-flat equipment (1)comprises at least one device (B, 24, 22, 23, 21, 20, 25, 26) forinfluencing the rotational speed of the roller (16), said device (B, 24,22, 23, 21, 20, 25, 26) comprising means (9) for providing a torque (B,24), which (B, 24) can be transferred onto the roller (16) by means oftransfer devices (22, 23, 21, 20), characterized in transfer devices(22, 23, 21, 20), which allow a slip between the roller (16) and thedevices (24) for providing a torque.
 2. Lay-flat equipment (1) accordingto claim 1 characterized in that the transfer devices (22, 23, 21, 20)comprise a coupling (25), using which the roller (16) and the means (24)for providing a torque can be separated.
 3. Lay-flat equipment (1)according to claim 1 characterized in that the transfer devices (20-23)comprise a location (21), at which the torque is transferred using aforce-fit connection.
 4. Lay-flat equipment (1) according to claim 3characterized in that the force-fit connection comprises at least one ofthe following characteristics: a hydraulic coupling a friction coupling.5. Lay-flat equipment (1) according to claim 2 characterized in that theforce-fit connection contains at least one magnet (34, 35).
 6. Lay-flatequipment (1) according to claim 2 characterized in that first forceflow surfaces (37) are assigned to the roller (16) and second force flowsurfaces (36) are assigned to the means for providing a torque (B, 24),said force flow surfaces (36, 37) being turned towards one another andwhich (36, 37) define the force-fit connection (27), wherein the surfaceof the opposite overlap of the first and second force flow surfaces (36,37) defines the amount of the maximum torque transmission and whereinthe surface of the opposite overlap of the first and second force flowsurfaces (36, 37) can be changed by a relative movement of the first andsecond force flow surfaces (36, 37).
 7. Lay-flat equipment (1) accordingto claim 1 characterized in that several transfer devices (20-23) areprovided.
 8. Lay-flat equipment (1) according to claim 6 characterizedin that several transfer devices (20-23) are provided and the surface ofthe opposite overlap of the first and the second force flow surfaces(36, 37) of the transfer devices of several rollers (16) can be changedby a common relative movement of the first and second force flowsurfaces (36, 37) of these rollers (16).
 9. Lay-flat equipment (1)according to claim 1 characterized in that a transfer device (20-23)transfers torque to several rollers (16).
 10. Lay-flat equipment (1)according to claim 5 characterized in a force-fit connection (27), whichcontains at least one electromagnet (35), which (35) is connected to apower controller (32) using which the current intensity in the coils ofthe electromagnet (35) and thus the field intensity generated by theelectromagnet (35) can be changed.